Good question - even though you're not into tattoos yourself, you're asking out of curiosity & an interest in the u will get, rather than just to knock people with tattoos. Thanks for that.
My own tattoos r all things which wo not date or lose their appeal in the same way as the example u cite. You're right, some people do get these kinds of tattoos, of things that r currently popular. I can not answer for them or their long-term feelings about their art. But for myself, I've always been completely aware that my tattoos would be permanent, & completely comfortable with this because I've been careful in the decisions I've made. For the most part, my tattoos represent aspects of my life or concepts I want to remind myself of, so even if my life & interests change over time, they will still be relevant.
I had my first tattoo done 11 years ago & do not regret it, or the subsequent ones I've had done, at all. Although I like the designs, the meanings that they have for me raise them above the level of something that could be affected by changing tastes. I suppose u could compare this to the place tattooing had in many cultures around the world, where it was used to mark transitions, as a rite of passage. That might sound like a rather overblown way of putting it, & it is a much more personal thing rather than a social ritual, but there is something of the same idea involved. Where a tattoo has significance in that way, it rises above 'like' & 'dislike', & becomes a part of who u are.
That is not to say that tattoos without this kind of significance r not perfectly valid - they certainly can be. Many people have beautiful tattoos just because they enjoy their art, & it makes them happy, & they do not regret them, either. But I wanted to give u my perspective, as a way to help u understand tattoos better.
Hope this makes sense!